Viral infection significantly impacts all forms of life. Since every virus and bacteriophage requires correct organization of its capsid proteins (CPs), the mechanisms by which these CPs assemble must ultimately be determined in order to devise efficacious methods to circumvent infection or its spread. Bacteriophage P22 shares features of assembly and a high degree of structural conservation among the major CPs of numerous dsDNA viruses, including the human herpesviruses, and will serve as a model system in the proposed research. We will study the stages of infection in P22-infected Salmonella, employing both electron tomography of samples treated by High Pressure Freezing and Freeze Substitution (HPF/FS) and fluorescence microscopy. Initially, our focus will be on visualizing early events of infection, including P22 attachment to cells and subsequent release of the minor proteins gp16, gp7, and gp20 into cells. Ultimately, these methods will help us characterize many stages of the virus life cycle, including those that occur during the end of the cycle such as procapsid assembly and maturation. In addition, we propose to employ electron cryo-microscopy on single particles to determine the structural transitions that occur in the major capsid protein as the virion matures. Adding and mastering these powerful techniques to my repertoire will bolster my path towards a faculty position at a top tier institution.